A groundwater deficit is growing in key agricultural areas of California. The double-whammy of the extended drought and longer-term reductions in surface water deliveries for environmental needs has pushed many farmers into using ever-more groundwater, at rates that can’t be sustained. In average years, about a third of water used by California’s farms is groundwater—and much more during droughts like this one. In some basins (especially those in major farming regions in the southern San Joaquin Valley and the Central Coast), groundwater withdrawals have long exceeded the pace of replenishment, thus shrinking our most reliable supply for times of drought.
The groundwater law enacted last fall gives local agencies the tools and authority they need to develop and implement sustainable groundwater management plans. Once agencies put these plans in place, they will have 20 years to achieve sustainability—until 2040 for the most stressed groundwater basins. The state can step in if these agencies fail to act.
Despite the seemingly generous timeline for compliance, the law’s goals will be challenging to meet. By June 2017, groundwater users in each basin need to designate a local groundwater sustainability agency that will be responsible for local oversight. And by January 2020, these agencies need to start implementing their sustainability plans. In most places, getting this preparatory work done will require significant additional technical analysis to understand how the basins’ supply and demand work. It will also require coming to agreement on how to collectively manage what has largely been considered an individual resource, with each user able to pump as much as he or she can put to beneficial use.
The drought has made it clear that the status quo is unsustainable. Declines in groundwater levels are resulting in higher energy costs to pump water from deeper depths, sinking lands, and wells going dry in some places.
The groundwater law was not widely embraced by the farm community; indeed, not a single legislator from the San Joaquin Valley voted in favor of it. Yet California farming needs to strengthen groundwater management to support the growing investments in highly valuable fruit and nut orchards and vineyards, which must be watered each year. It’s essential to manage groundwater so that it’s available during droughts, and the new law provides a pathway to do this.
Bringing basins into balance will require creative approaches to basin replenishment. Many irrigation districts are already taking critical steps in this direction. For example, agencies on the east side of the San Joaquin Valley manage surface and groundwater resources jointly to encourage groundwater basin replenishment in wet years. Some districts in the San Joaquin Valley and in the Central Coast have begun recharging basins with recycled wastewater from neighboring urban areas. Another promising approach is allowing floodwaters to spread on fields normally watered by drip irrigation.
A number of technical challenges will need to be addressed. For example, not every aquifer can be recharged, and in many areas, recharge is slow. Much of California’s water conveyance infrastructure was designed for use with surface reservoirs as the main water source, not groundwater. And over time, widespread conversions from flood to drip irrigation methods have allowed farmers to stretch limited surface water supplies, but this is also reducing opportunities for groundwater recharge. New institutional and financial arrangements will be needed to optimize groundwater storage.
Like nearly everything to do with the state’s water management, the solutions to groundwater recharge will require a deft blend of management, infrastructure and policy changes. The new law appropriately puts locals in the driver’s seat for managing a local resource. But the state must play a central role in supporting this transition, with financial and technical support. Allocating funds from Proposition 1, the water bond approved by California voters last November, will be a good start.